Iodophor preparations are known and are commercially available. These preparations which are complexes of iodine with an organic substance such as a polymer, surface active agent, alcohol, polyol or water soluble solvent possess considerable advantages over iodine, iodine tinctures, etc. The most important iodophor preparation is that of polyvinylpyrrolidone-iodine (PVP iodine), which is a commercially available preparation found in a variety of forms. This preparation has recognized good microbicidal properties.
However, these iodophor preparations, even including PVP iodine, also possess disadvantages which are important for the use, particularly with regard to storage stability, reliable effectiveness over an extended period and reproducibility, i.e. manufactured to a consistently good effective quality.
It has been found that predictable good microbicidal effectiveness of iodophor preparations can be assured by providing compositions of iodophor preparations comprising the iodophor-forming organic substance such as polyvinylpyrrolidone, complex bound iodine, that is iodine bound thereto, free iodine and iodide ions with a ratio of total iodine (complex bound iodine plus free iodine) to iodide of between 2:1 to 10:1, preferably 2:1 to 6:1, most preferably 2.1:1 to 3.6:1. The adjustment of this iodine to iodide ratio was effected by chemical oxidation, particularly by the addition of a source of iodate ions.